1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocenium tetracyanoethylenide, [Fe(C5EtMe4)2][TCNE], a charge-transfer salt magnetic solid with a novel structural motif

1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocene has been utilized as a one-electron donor in the synthesis of a tetracyanoethylene charge-transfer salt, [Fe(C₅EtMe₄)₂]⁺[TCNE]⁻. Structural characterization shows that it adopts an arrangement of anions and cations completely different from the usual π stacking seen in analogous decamethylferrocenium compounds. The TCNE radical sits along side of the ferrocene, nearly perpendicular to the planes of the C₅ rings. The nearly square geometry of the TCNE anion creates disorder over two orientations. [Fe(C₅EtMe₄)₂]⁺[TCNE]⁻ is a simple paramagnet exhibiting neither long-range magnetic order nor slow paramagnetic relaxation to the lowest measured temperatures (ca. 1.8 K) as determined by both ac and dc magnetic susceptibility and Mössbauer spectroscopy (ca. 1.3 K).     

Facile formation of a heterobimetallic cluster with a cubane-like [Mo3S4Cu] core

Reaction of the cluster salt [(η⁵-Cp^′)₃Mo₃S₄][pts] ([1][pts], Cp^′=methylcyclopentadienyl; pts=p-toluenesulfonate) with CuCl yielded a new heterobimetallic cluster, [(η⁵-Cp^′)₃Mo₃S₄Cu(Cl)][pts] ([2][pts]). X-ray crystal structure determination of [1][pts] and [2][pts] showed that the incorporation of CuCl into the Mo₃S₄ cluster core has only minor consequences on the Mo-Mo and Mo-S distances. The metal atoms in the cluster core of [2]⁺ form an almost regular tetrahedron. The [2]⁺ cation conforms to an idealized C_3v symmetry ignoring the Cp^′ groups since the Cu-Cl bond is almost aligned with the axis defined by the Cu-S(4) cube diagonal.     

BEDT-TTF salts of the unsymmetrical [M(tfadt)2] dithiolene complexes (M = Ni, Au; tfadt = S2C2(CN)(CF3))

Two closely related 1:1 salts are obtained upon electrocrystallization of BEDT-TTF (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene) in the presence of the isosteric [M(tfadt)₂]⁻ dithiolene complexes (tfadt: 1-trifluoromethyl-2-cyano-1,2-dithiolato), which essentially differ by their spin state, S = 0 in [Au(tfadt)₂]⁻, S = 1/2 in [Ni(tfadt)₂]⁻. In both [BEDT-TTF][M(tfadt)₂] salts, the BEDT-TTF radical cations form chains with a strong lateral overlap and strong antiferromagnetic interactions while the paramagnetic anions in the nickel-containing salt [BEDT-TTF][Ni(tfadt)₂] are essentially non-interacting. The structural differences between the nickel and gold complexes are analyzed and discussed.     

Pressure-tuning infrared spectra of the three Magnus’ Green salts, [Pt(NH3)4][PtCl4], [Pt(ND3)4][PtCl4] and [Pt(NH3)4][PtBr4]

Pressure-tuning infrared spectra (up to ca. 40 kbar) are reported for Magnus’ Green salt, [Pt(NH₃)₄][PtCl₄] and two of its derivatives, [Pt(ND₃)₄][PtCl₄] and [Pt(NH₃)₄][PtBr₄]. The spectroscopic data indicate that there is restricted rotation of the coordinated ammonia groups about the Pt-N bonds in the complexes. It is possible that this restricted rotation is due to the presence of weak hydrogen bonding to the halogens, i.e., N-H?X (X = Cl, Br) interactions.     

The new enneanuclear nickel carbonyl anion [Ni9(CO)16] and its relationships with the [Ni12(CO)21] and [Ni6Rh3(CO)17] clusters

The reaction of [N(PPh₃)₂]₂[Ni₆(CO)₁₂] with Cu(PPh₃)_xCl (x=1, 2), as well as the degradation of [N(PPh₃)₂]₂[H₂Ni₁₂(CO)₂₁] with PPh₃, affords the new and unstable dark orange–brown [N(PPh₃)₂]₂[Ni₉(CO)₁₆].THF salt in low yields. This salt has been characterized by a CCD X-ray diffraction determination, along with IR spectroscopy and elemental analysis. The close-packed two-layer metal core geometry of the [Ni₉(CO)₁₆]²⁻ dianion is directly related to that of the bimetallic [Ni₆Rh₃(CO)₁₇]³⁻ trianion and may be envisioned to be formally derived from the hcp three-layer geometry of [Ni₁₂(CO)₂₁]⁴⁻ by the substitution of one of the two outer [Ni₃(CO)₃(μ−CO)₃]²⁻ layers with a face-bridging carbonyl group.     

Host-guest properties of the trinuclear arene-ruthenium cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]

The trinuclear arene-ruthenium cluster cation [H₃Ru₃(C₆H₆)(C₆Me₆)₂(O)]⁺, containing a μ₃-oxo cap and three arene ligands that span a hydrophobic pocket above the metal skeleton, has been crystallised as tetrafluoroborate salt in the presence of various guest molecules. The host-guest complexes have been characterised by single-crystal X-ray structure analysis. With chloroform as the guest molecule, a CHCl₃ molecule sits perfectly in the hydrophobic pocket, the hydrogen atom being encapsulated inside the cavity. When dioxane is added during the crystallisation process, the cluster forms infinite chains which are connected by a complex network of hydrogen bonds involving the μ₃-oxo ligand, water and dioxane molecules. Interestingly, in the presence of phenol, a water molecule is hydrogen-bonded between the μ₃-oxo ligand and the phenol molecule, forming a one-dimensional μ₃-O ? H₂O ? HO hydrogen-bonded chain. Finally, with benzoic acid, a head-to-tail host-guest chain is obtained, the phenyl ring being incorporated in the hydrophobic pocket, while the acid group is hydrogen-bonded to the μ₃-oxo ligand.     

The synthesis, fluctionality and structural characterization of ReMo3H4(CO)12

The reaction of ReH₉²⁻ with Mo(diglyme)(CO)₃ leads to the formation of the mixed metal cluster trianion, ReMo₃H₄(CO)₁₂³⁻. This species has been characterized analytically, spectroscopically and through X-ray diffraction analysis. A pseudo-tetrahedral arrangement of M(CO)₃ fragments is adopted, such that each set of three carbonyl ligands eclipses the adjacent three tetrahedral edges, an apparent result of the location of the hydride ligands on the tetrahedral faces. Variable temperature NMR studies revealed a fluctional process for some of the carbonyl ligands, but not for the hydrides. Crystal data for [Me₄N]₃[ReMo₃H₄(CO)₁₂]·THF; space group P2₁/n, a = 12.157(2), B = 21.480(4), C = 15.964(3) Å, β = 98.26(1)°, Z = 4, R = 0.067 and R_w = 0.076.     

Hydrothermal synthesis and crystal structure of one-dimensional organic/inorganic hybrid material: [Mo4O12(2,2′-bpy)3]n

A new polyoxomolybdenum compound [Mo₄O₁₂(2,2′-bpy)₃]_n (1) (2,2′-bpy = 2,2′-bipyridine) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single crystal X-ray diffraction. The solid state structure is a 1D chain with a repeat unit of three corner-sharing {MoO₄N₂} octahedra and one {MoO₄} tetrahedron.     

Hydrothermal synthesis and structure of [Ni(tpyrpyz)2]2[Mo4O12F2][Mo6O19] · 2H2O, a material exhibiting an unusual tetranuclear polyoxofluoromolybdate cluster [Mo4O12F2]

The hydrothermal reaction of a solution of Ni(CH₃CO₂)₂ · 4H₂O, MoO₃, tetra-4-pyridylpyrazine, H₂O₃PCH₃, and HF at 200 °C for 96 h yields orange crystals of [Ni(tpyrpyz)₂]₂[Mo₄O₁₂F₂][Mo₆O₁₇] · 2H₂O (1 · 2H₂O). The structure consists of discrete {Ni(tpyrpyz)₂}²⁺ cations and {Mo₆O₁₉}²⁻ and {Mo₄O₁₂F₂}²⁻ anionic clusters. The hexamolybdate is the well-documented octahedron of octahedra, that is, six {MoO₆} octahedra in a compact edge-sharing arrangement. The novel oxyfluoride cluster {Mo₄O₁₂F₂}²⁻ features two {MoO₄F₂} octahedra, sharing the edge defined by the fluoride ligands; the octahedral Mo sites corner-share to two {MoO₄} tetrahedra in the μ₂-O, O^′ bridging mode.     

A new bonding mode for the bicyclic guanidinate, [hpp], in the tetrametallic yttrium oxide cluster, Y4(hpp)8Cl2(μ4-O)

Oxygen incorporation in the product of the reaction between YCl₃ and the lithium salt of 1,3,4,6,7,8-hexahydro-2Hpyrimido[1,2-a]pyrimidine (hppH) afforded the tetrametallic cluster Y₄(hpp)₈Cl₂(μ₄-O), in which four of the guanidinate anions are involved in a previously unreported μ,η²,η²-bridging mode between two metal centres.     

Reaction of a bulky phosphite with [Ru3(CO)12]: The molecular structure of one of the decomposition products

Mono- and bis-substituted phosphite complexes [Ru₃(CO)_12−x L_x] (L = tris(2,4-di-tert-butylphenyl) phosphite; x = 1, 2) were synthesized by simple substitution reactions, and were characterized by spectroscopic methods. The monosubstituted ruthenium complex disproportionates in acetone producing a mononuclear ruthenium complex as one of the decomposition products. Single crystal X-ray diffraction analysis established the molecular structure of this new compound.     

Coordination chemistry of copper-molybdates with alkoxide ligands: The {Mo4O10(OMe)6} and [Mo2O4{RC(CH2O)3}2] clusters as building blocks

The reactions of the Keplerate super cluster [Mo₁₃₂O₃₇₂(CH₃CO₂)₃₀(H₂O)₇₂]⁴²⁻ with a Cu(II) source and an organonitrogen donor in methanol/DMF solutions yielded a series of bimetallic organic-inorganic oxide hybrid materials, including the molecular species [Cu(phen)₂MoO₄] (1) and [{Cu(terpy)}₂(MoO₄)₂] (2) and a series of materials constructed from the tetranuclear building block {Mo₄O₁₀(OMe)₆}²⁻: the molecular [{Cu₂(phen)₂(O₂CCH₃)₂ (MeOH)}Mo₄O₁₀(OMe)₆] (3), [{Cu(terpy)(O₂CCH₃)}₂Mo₄O₁₀(OMe)₆] (4) and [{Cu(terpy)Cl}₂Mo₄O₁₀(OMe)₆] (5), the one-dimensional phases [{Cu(bpy)(HOMe)₂}Mo₄O₁₀(OMe)₆] (6), [{Cu(bpy)(DMF)₂}Mo₄O₁₀(OMe)₆] (7), [{Cu(bpa)(DMF)₂}Mo₄O₁₀(OMe)₆] (8), [{Cu(phen)(DMF)₂}Mo₄O₁₀(OMe)₆] (9) and [{CuCl(dpa)}₂Mo₄O₁₀(OMe)₆] (10), and the two-dimensional material [{Cu₂(DMF)₂(pdpa)}{Mo₄O₁₀(OMe)₆}₂] (11). When methanol is replaced by the tridentate alkoxide tris-methoxypropane (trisp), the {Mo₂O₄(trisp)₂}²⁻ cluster building block is observed for [Cu(phen)Mo₂O₄(trisp)₂] (12), [Cu(bpa)(DMF)Mo₂O₄(trisp)₂] (13) and [{Cu(bpy)(NO₃)}₂Mo₂O₄(trisp)₂] (14).     

A new hexanuclear rhenium cluster complex with six terminal acetate ligands: Synthesis, structure, and properties of K4[Re6S8(CH3COO)6]·8H2O

A room-temperature reaction between [Re₆S₈(OH)₆]⁴⁻ and acetic acid in an aqueous solution resulted in the substitution of all terminal hydroxo groups by acetate ligands, affording a new hexanuclear anionic rhenium cluster complex [Re₆S₈(CH₃COO)₆]⁴⁻. The complex was isolated as a potassium salt with the composition of K₄[Re₆S₈(CH₃COO)₆]·8H₂O (1) and characterized by X-ray single-crystal diffraction and elemental analyses, IR, ¹H NMR, UV-Vis, and luminescence spectroscopies.     

Mixed-metal butterfly acetamidediato clusters derived from a highly reactive ruthenium oxo cluster: synthesis and characterization of [(PPh3)2N][MRu3(CO)12(η-μ3-NC(μ-O)CH3)], (M = Mn or Re)

Analogy with the isolable oxo cluster [Fe₃(CO)₉(μ₃-O)]²⁻, which is structurally interesting and synthetically useful, prompted the present attempt to synthesize its ruthenium analog. Although the high reactivity of [Ru₃(CO)₉(μ₃-O)]²⁻ (I) prevented its isolation, the reaction of this species with [M(CO)₃(NCCH₃)]⁺, where M = Mn or Re, yields [PPN][MRu₃(CO)₁₂(η²-μ₃-NC(μ-O)CH₃]⁻. The high nucleophilicity of the oxo ligand in [Ru₃(CO)₉(μ₃-O)]²⁻ (I) appears to be responsible for the conversion of acetonitrile to an acetamidediato ligand and for the instability of I. The crystal structure of [PPN][MnRu₃(CO)₁₂(η²-μ₃-NC(μ-O)CH₃)]] reveals a hinged butterfly array of metal atoms in which the acetamidediato ligand bridges the two wings with μ₃-N bonding to an Mn and two Ru atoms, and μ-O bonding to an Ru atom.     

The coordination chemistry of cationic main group clusters: syntheses and structures of [Fe3(Se2)2(CO)10] and [Fe4(Se2)3(CO)12]

The reactions of the polysulfur and selenium cationic clusters S₈²⁺ and Se₈²⁺ with various iron carbonyls were investigated. Several new chalcogen containing iron carbonyl cluster cations were isolated, depending on the nature of the counteranion. In the presence of SbF₆⁻ as a counterion, the cluster [Fe₃(E₂)₂(CO)₁₀] [SbF₆]₂·SO₂ (E = S, Se) could be isolated from the reaction of E₈²⁺ and excess iron carbonyl. The cluster is a picnic-basket shaped molecule of two iron centers linked by two Se₂ groups, with the whole fragment capped by an Fe(CO)₄ group. Crystallographic data for C₁₀O₁₂Fe₃Se₄Sb₂F₁₂S (I): space group monoclinic P2₁/c, A = 11.810(9), b = 24.023(6), c = 10.853(7) Å, β = 107.15(5)°, V = 2942(3) ų, Z = 4, R = 0.0426, R_w = 0.0503. When Sb₂F₁₁⁻ is present as the counterion, or Se₄[Sb₂F₁₁]₂ is used as the cluster cation source, a different cluster can be isolated, which has the formula [Fe₄(Se₂)₃(CO)₁₂] [SbF₆]₂·3SO₂. The dication contains two Fe₂Se₂ fragments bridged by an Se₂ group. Crystallographic data for C₁₂O₁₈Fe₄Se₆Sb₂F₁₂S₃ (III): space group triclinic , b = 18.400(9), C = 10.253(4) Å, = 93.10(4), β = 103.74(3), γ = 93.98(3)°, V = 1995(1) ų, Z = 2, R = 0.0328, R_w = 0.0325. The CO stretches in the IR spectrum all show a large shift to higher wavenumbers, suggesting almost no τ backbonding from the metals. This also correlates with the observed bond distances. All the compounds are extremely sensitive to air and water, and readily lose SO₂ when removed from the solvent. Thus all the crystals were handled at −100°C. The clusters seem to be either insoluble or unstable in all solvents investigated.     

Synthesis, crystal structure and magnetic properties of a novel complex Ni(NIT2-thz)3(ClO4)2

A novel Ni(II)-nitronyl nitroxide-substituted thiazole complex, Ni(NIT2-thz)₃(ClO₄)₂ (NIT2-thz = 2-(2′-thiazole)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) was synthesized and characterized structurally and magnetically. It crystallizes in the monoclinic space group P2₁c. The metal coordination sphere is fully occupied by three chelating nitroxide ligands, showing a distorted octahedral geometry. The complex molecules were connected as 1-D chain structure by the intermolecular interaction. Magnetic studies show that antiferromagnetic couplings occurred between the nickel(II) ion and the organic radicals, and ferromagnetic between the adjacent molecules.     

Preparation and structures of the cluster dimers consisting of Rh2Mo2S4 single-cubane units connected by two bidentate N-donor ligands

Reactions of a single-cubane cluster [{Rh(cod)}₂{MoCl(dtc)}₂(μ₃-S)₄] (cod = 1,5-cyclooctadiene, dtc = diethyldithiocarbamate) with 1 equiv. of L (L = pyrazine, 4,4′-bipyridyl, trans-1,2-bis(4-pyridyl)ethylene) in the presence of 2 equiv. of AgBF₄ in CH₂Cl₂ gave doubly bridged double-cubane clusters [({Rh(cod)}₂{Mo(dtc)}₂(μ₃-S)₄)₂(μ-L)₂][BF₄]₄, whose structures were determined by the single-crystal X-ray analysis.     

Synthesis, magnetism and X-ray structures of [Cu(2-aminopyrimidine)2(μ-OH)(CF3SO3)]2(2-aminopyrimidine)2, a new hydroxo-bridged dinuclear Cu(II) compound generating extremely small antiferromagnetism

The synthesis, optical and magnetic properties and X-ray crystal structure of [Cu(2-aminopyrimidine)₂(OH)(CF₃SO₃)]₂(2-aminopyrimidine)₂, a new dinuclear hydroxo-bridged copper(II) compound with a CuOCu angle of 97.96° and a very small antiferromagnetic interaction for which the singlet-triplet exchange parameter J, is described. The magnetic exchange coupling is almost negligible and, depending on the actual sample, varies from −1.8 to −7.2 cm⁻¹.     

Hydrothermal synthesis and structural characterization of a network oxide constructed from {Mo12O34(O3AsC6H5)4} clusters and {Cu(terpy)} subunits

The hydrothermal reaction of MoO₃, [Cu(CH₃CO₂)₂] · H₂O, 2,2^′:6^′,2″-terpyridine (terpy), H₂O₃AsC₆H₅, H₂O and H₂SO₄ yields aqua colored crystals of [{Cu(terpy)}₂Mo₁₂O₃₄(O₃AsC₆H₅)₄] · 2.25H₂O (1 · 2.25H₂O). The two-dimensional structure of 1 is constructed from {Mo₁₂O₃₄(O₃AsC₆H₅)₄}⁴⁻ clusters linked through {Cu(terpy)}²⁺ subunits. Each Cu(II) site exhibits {CuN₃O₂} coordination geometry and links two adjacent clusters. In turn, each cluster is associated with four Cu(II) sites through {MoO · Cu} interactions.